Extension of rubber



Patented June 19,

Reilly Tar & Chemical apolis, Ind., a corporation Corporation, Indiumof Indiana No Drawing. Application February 5, 1943, Serial No. 474,849

2 Claims. (Cl- 2601-36) This invention relates to anew rubber extender, to the method of eilectively utilizing it, and to new-rubber material and rubber products embodying it. I

In these critical times, every eiiort is being made to extend our small and dwindling rubber supply. Extensive research is being conducted to find ways of making that rubbersupply go farther. I a

My present invention does that.

I have found that by incorporating a small amount of acenaphthylene in. a larger amount of a rubber-by which term I mean a sulfur vulcanizable rubber, including both natural rubber and so-called synthetic rubbers ofthe Buna S (butadiene-styrene copolymer), Buna N (butadiene-acrylonitrile copolymer), and copolymers of vinyl pyridines and butadiene-there is obtained an increased amount of rubber material; and that on vulcanizing that rubber material a vulcanized rubber product is obtained which has properties not undesirably altered from those of the vulcanized rubber itself, and in some caseseven better than those of the vulcanized rubber.

itself. The amount of acenaphthylene may be anything up to about 50% by weight of the amount of the rubber;

For instance, I have found that by incorporatraw crepe rubber, with such other ingredients as are necessary or common in vulcanizing, and vulcanizing the mixture, the resultant vulcanized rubber product has increased elongation and increased tensile strength as compared with a prodnot exactly similar save for the omission of the acenaphthvlene.

Similarly, I have found that by incorporating I 20-30 Parts of acenaphthylene in 100 parts of a synthetic rubber of thetype of Buna S, Buna N, and copolymers of vinylpyridine and butadiene (described in the co-pen'ding application of William H. Rieger and myself, Serial No. 450,920, filed July 14, 1942), and also putting in the mixture necessary or desirable ingredients for vulcanlzation, upon such vulcanization a product is obtained which has increased softness and increased elongation as comparedwith exactly the I same product with the acenaphthylene left out.

The following are examples of my invention:

Example 1 Raw crepe rubber is compounded, on ordinary rubber rolls, in accordance with the following formula:

I Parts Crepe rubber- 100' Stearic a 4 Zinc oxide 5 Carbon Acenaphthylene 25 Sulfur 3 Mercaptobenzothiazole l in: 25 parts of accenaphthylene in 100 parts of The compounded rubber so produced is vulcanized under pressure for one hour at about 140 to 145 C. 1

The-vulcanized rubber product thus obtained, containing acenaphthylene as noted, is found to have a higher elongation and a higher tensile strength than has an exactly corresponding rubber composition with the acenaphthylene omitted.

Thus the rubber product is not only increased in amount over that obtained when the acenaphthylene is omitted, but the product is better both in tensile strength and in elongation.

Example 2,

A ynthetic rubber of the Burns, N type, such as the so-called Hycar ore-15, is compounded on ordinary rubber rolls in accordance with the following formula:

Parts Hycar 03-1 Stearic a 2 Zinc. oxide 10 Channel black Acenaphthylene 40 Mercaptobenzothiazole 1 Sulfur 1 The compounded rubber so obtained is canized under about 145 C.

vul-

pressure for about one hour at The vulcanized rubber product so obtained has greater elongation and is softer than is an otherwise exactly corresponding rubber product with the acenaphthylene omitted.

Thus in this example also the amount of rubber product is increased, and at the same time the vulcanized rubber product has greater elongation and greater softness.

Example 3 Example 4 Examples 2 and 3 are repeated, save that instead of usin a synthetic rubber of the Buna. N or Buna S pe, I use a synthetic rubber of the type shown in the aforesaid Cislak 8: Rieger patent application -that is, a copolymer of a vinylpyridine and butadiene. Here again, as in Exampies 2 and 3, the product containing the acenaphthylene has increased softness and increased elongation over exactly the same product with the-acenaphthylene omitted.

I claim as my invention.

1. A rubber product, which consists in a vulcanized rubber material containing a sulfur vulcanizable rubber and a smaller amount of acenaphthylene.

2. A rubber.material, consisting in a mixture containing a sulfur vulcanizable rubber and I smaller-amount of acenaphthylene.

FRANCIS E. CISLA-K. 

